This project is for the study of the segregation distorter phenomenon in Drosophila melanogaster, first with regard to its genetic and developmental basis in order to uncover general principles involving the genetic control of spermatogenesis, and second with regard to its populational and evolutionary consequences with an eye to using non-Mendelian segregation as a tool in the genetic control of populations of insect pests. Theoretical models pertinent to meoitic drive or selection will be investigated as appropriate. Current experimental work involves studying the suppression of segregation distortion by actinomycin D and the synthesis of sperm-specific histones in segregation distorter males. Population studies include those of a long-term population cage and of natural populations in North Carolina, Texas, and elsewhere. Theoretical studies include non-Mendelian segregation and its modifiers as well as stochastic selection in a more general context.